Choropleth Map

Choropleth map -  Provides an easy visualization of data measurement across a geographic region.

http://www.agcensus.usda.gov/Publications/2002/Ag_Atlas_Maps/Crops_and_Plants/index.asp - map #02-M259
http://www.nass.usda.gov/research/atlas02/Crops/Fruits,%20Tree%20Nuts,%20Berries,%20Nursery%20and%20Greenhouse%20Crops/Total%20Acres%20of%20Land%20in%20Orchards-choropleth%20map.gif
The above map displays total acres that were orchards in the US in 2002

Dot Distribution Map

Dot Distribution Map - Great for showing populations.  There are 2 types a one to one dot and a one to many.

http://www.census.gov/geo/www/mapGallery/2kpopden.html
http://www.census.gov/geo/www/mapGallery/images/small2kden.jpg
The above map is a 1 to 7500 person dot distribution map of data collected during the 2000 US Census.

Hypsometric Map

Hypsometric Map - Shows elevation by means of shading and tinting.

http://igitur-archive.library.uu.nl/dissertations/2008-1010-200655/ - Annex 4A
http://igitur-archive.library.uu.nl/dissertations/2008-1010-200655/Annex4A.jpg
The above image is a hypsometric map of cuba at a 1:1,000,000 scale.